好程序员大数据培训技术为大家分享Scala系列之方法的嵌套和方法多态

方法里嵌套定义其他方法

示例1

object EmbedDemo {
  
  def add3(x:Int,y:Int,z:Int)={
    def add2(x:Int,y:Int)={
      x+y
    }
    add2(add2(x,y),z)
  }

  def main(args: Array[String]): Unit = {
     println(add3(1,2,3)) //6
  }
}

示例2

def factorial(x: Int): Int = {
def fact(x: Int, accumulator: Int): Int = {
      if (x <= 1) accumulator
      else fact(x - 1, x * accumulator)
    }  
    fact(x, 1)
 }

 println("Factorial of 2: " + factorial(2))
 println("Factorial of 3: " + factorial(3))

方法的多态

Scala里方法可以通过类型实现参数化，类似泛型。

def listOfDuplicates[A](x: A, length: Int): List[A] = {
  if (length < 1)
    Nil
  else
    x :: listOfDuplicates(x, length - 1)
}
println(listOfDuplicates[Int](3, 4))  // List(3, 3, 3, 3)
println(listOfDuplicates("La", 8))  // List(La, La, La, La, La, La, La, La)